Dies for bending sheet metal



May 15, 1962 D. M. SLATER 3,034,559

DIES FOR BENDING SHEET METAL Filed flab. 25, 1960 s Sheets-Sheet 1INVENTOR 5 May 15, 1962 D. M. SLATER 3,

DIES FOR BENDING SHEET METAL Filed Feb. 25, 1960 v 3 Sheets-Sheet 2lNVENTO RI flax/gm! 12 7/2 32 5; M42

ATI'OIRNEY May 15, 1962 D. M. SLATER 3,034,559

DIES FOR BENDING SHEET METAL Filed Feb. 25, 1960 3 Sheets-Sheet 3 17/5 I\j INVENTORZ fax/ ak AZ JZ/FE? 69 United States Patent 3,034,559 DIESFOR BENDING SHEET METAL Douglas M. Slater, Nashville, Tenn., assignor toJohn W. McDougall Company, Inc., Nashville, Tenn., a corporation ofTennessee Filed Feb. 23, 1969, Ser. No. 10,408 13 Claims. (Cl. 153-21)This invention relates to dies for bending sheet met-a1 and moreparticularly to dies for forming multiple deep bends in sheet metal tomake various types of slip locks for duct work.

Heretofore, the manufacture of slip locks of the 8- type for heating,ventilating and air 'conditioning duct work, has required six or sevendifferent bending operations on conventional sheet metal bendingmachines. Moreover, such bending operations require a high degree ofskill and care in order to bend the metal according to specifieddimensions.

It is therefore an object of this invention to provide special sets ofdies for forming the slip looks from a flat sheet of metal in twobending operations, which will require a minimum of skill on the part ofthe die operator and yet obtain a high degree of accuracy and uniformityin the finished slip locks.

Another object of this invention is to provide sets of dies which may beincorporated in a conventional press brake.

Another object of this invention is to provide -a bending set of diesand a flattening set of dies, both of which may be incorporated in thesame press brake to carry out their individual functions simultaneouslyon different sheets of metal.

A further object of this invention is to provide a set of bending diesand a set of flattening dies which may be adapted for forming at leastfour types of slip locks.

Another object of this invention is to provide sets of dies for formingslip locks of various dimensions.

Another object of this invention is to provide sets of dies for formingmultiple deep bends in sheet metal with a minimum of travel and withoutdanger of tearing the metal at their bend points.

Further objects and advantages of the invention will be apparent fromthe following description taken in conjunction with the drawings,wherein:

FIG. 1 is an end elevation of a press brake incorpm rating the bendingdies made in accordance with this invention with the upper die in raisedinoperative position;

FIG. 2 is an enlarged sectional elevation of the bending dies of FIG. 1in operative position;

FIG. 3 is an end view of a bent piece of sheet metal formed by the diesof FIGS. 1 and 2;

FIG. 4 is an end elevation of the flattening dies made in accordancewith this invention in various operative positions;

FIG. 5 is a sectional elevation of a 1-inch standing S-bar slip lockformed from dies of FIG. 4, and in operative position locking theadjacent ends of connecting ducts;

IG. 6 is a sectional elevation of a modification of the bending dieswith the upper die in raised position;

FIG. 7 is an end view of a bent piece of sheet metal formed by the diesof FIG. 6;

FIG. 8 is a view similar to FIG. 4, disclosing the flattening diesoperating upon the bent piece of sheet metal disclosed in FIG. 7;

FIG. 9 is a viewsimilar to FIG. 5, disclosing a 1 /2- inch standingS-b-ar slip lock;

FIG. 10 is a view similar to FIG. 9, disclosing a 1 /2- inch reinforcedstanding S-bar slip lock;

FIG. 11 is an end elevation of another modified form of the bendingdies;

FIG. 12 is an end view of a piece of bent sheet metal formed by the diesof FIG. 11;

FIG. 13 is an end elevation of the flattening dies preparatory tooperation upon the bent piece of sheet metal disclosed in FIG. 12;

FIG. 14 is a view similar to FIGS. 5, 9, and 10, disclosing a fiat Sslip lock.

Referring now to the drawings in more detail, FIG. 1 discloses aconventional press brake 20 having a vertically reciprocable upper head21 and a lower stationary die support 22. Removably fixed in thestationary support 22 is a first or lower bending die 23 having a topface of novel configuration. Removably fixed and depending from theupper head 21 is the second or upper bending die 24 having a bottom faceof a complementary configuration adapted to mate with the face of thelower die 23 when said upper head 21 has been reciprocated to its lowestposition. As best disclosed in FIG. 1, a piece of sheet metal 25, whichis to be bent into the desired shape, is placed in a substantiallyhorizontal position between the dies when the upper die 24 is in raised,inoperative position. The rear edge of the sheet metal 25 rests againstan upright abutment bar 26 fixed to the frame of the press brake 20 inadjustable spaced relation with the dies 23 and 24.

The top face of the lower bending die 23 comprises an upstandingV-shaped projection 30 flanked by a shallow channel-shaped recess 31 anda shallow V-shaped recess 32. The V-shaped projection 30 has a planeside face 33 which is parallel to the direction of movement of the upperdie 24, which is preferably vertical as disclosed in the drawings. Theother side face 34 of the projection 30 is likewise plane, but slopes ata substantial acute angle downward and away from the vertical face 33.The side faces 33 and 34 are joined by a gradually rounded portion 35which forms the upper extremity or tip of the projection 30. Thechannel-shaped recess 31 has a short side wall 36 which is likewiseparallel to the direction of movement of the upper die 24, or preferablyvertical. The recess 31 has a sloping plane bottom 37 which forms anobtuse angle with the vertical face 33. The vertical face 33 forms thecommon side of the projection 30 and the recess 31. The V-shaped recess32 likewise has a vertical side wall 38 of substantially the same heightas the side wall 36. The recess 32 likewise shares a common side face orwall 34 with the projection 30, and has a rounded bottom portion orvalley 39. The upper edge of the wall 36 is rounded in -a reverse curve40 which terminates in a sloping plane surface 41, preferably at anangle of approximately 45 to the vertical. In like manner, the top ofthe wall 38 forms a rounded portion 42 which terminates in a downwardlysloping plane surface 43 at substantially the same angle of 45 to thevertical. A portion of the bottom 37 adjacent the vertical wall 36 inthe recess 31 is provided with a threaded opening 44, fora purpose to bedescribed later.

The upper bending die 24 is provided with a V-shaped recess 50 flankedby projections 51 and 52, having common sides 53 and 54 and a roundedconnecting portion 55 of the same dimensions and configuration as theirmating counterparts 30, 31, 32, 33, 34, and 35 in the lower stationarydie 23. The fiat end surface 57 of the projection 51 is of the sameslope as and adapted to mate with the bottom 37 of the recess 31.Moreover, the projection 52 has a rounded tip 59 of the sameconfiguration as the bottom portion 39 of the recess 32. The front face53 of the upper die 24 is a plane vertical surface adapted to mate withthe vertical wall 38 of the recess 32 when the dies 23 and 24 engage.The rear wall 56 of the die 24 is recessed at 60 and provided with athreaded opening 61.

In accordance with the specifications of the ASI-IVE (American Societyof Heating and Ventilating Engineers), certain types of S-type sliplocks have upstanding reinforcing ribs. These ribs are generallystandardized at a he ght of either 1 inch or 1% inches. In order to makethe bending dies 23 and 24 adaptable to produce the reinforcing ribs ofeither height, insert blocks 62 and 63 are provided to be alternatelyemployed with the upper die 24 or the lower die 23, respectively, inorder to vary the effective height of the reinforcing rib.

When it is desired to produce an S-type Slip lock having a 1 inchreinforcing rib, the insert block 63 is placed along the bottom 37 ofthe recess 31 abutting the vertical wall 36 and secured in place bymeans of a screw 64 inserted through the aligned threaded openings 65and 44. The insert block 63 is provided with a front vertical face 66which reduces the effective width of the recess 31 to the sameconfiguration as the projection 51 of the upper die 24, as bestdisclosed in FIGS. 1 and 2.

In the arrangement disclosed in FIG. 2, the insert block 62 is left outof the recess 60 in order for the projection 51 to mate with the recess31 and bend the sheet metal 25 therebetween into a similar shape. Inthis particular modification, the length of the sloping end 57 and thelength of the bottom portion 37 between the faces 33 and 66 are eachabout one inch, with a tolerance of about 0.050 inch to permit the sheetmetal 25 to fit between the mating surfaces when the dies are engaged.By operating the'movable head 21 to thrust the die 24 downward to engagethe die 23, including the insert block 63, the piece of sheet metal 25will be bent into the shape 70 disclosed in FIG. 3. The bent shape 70forms an pen S-shaped portion having substantially parallel legs 1 and72 connected at opposite ends by an angular leg 73, and a reinforcingrib portion having a pair of legs 74 and 75 connected by a bent portion76.

When it is desired to produce a slip lock having a 1 /2 inch reinforcingrib, the insert block 63 is removed and the insert block 62 is placed inthe recess 60 by appropriate means such as a screw 68 inserted throughthe aligned threaded openings 69 and 61, as best disclosed in FIG. 6.Since the length of the bottom 37 of the recess 31 between its sidewalls 33 and 36 is preferably about 1 /2 inches and the length of thebottom of the block 62 is about /2 inch, the projection 51 and theinsert block 62 are adapted to fit snugly within the recess 31 to form astanding reinforcing rib of 1 /2 inches.

A second set of flattening dies 8t and 81, as best disclosed in FIG. 4,are adapted to be fixed to the stationary support 22 and the uppermovable head 21 of a press brake 20 in the same manner as the first setof bending dies 23 and 24. The dies 80 and 81 may be supported in aseparate press brake 20 from the dies 23 and 24 or they may be fixed endto end with the dies 23 and 24 in the same members 22 and 21 of thepress brake 20. The lower flattening die 89 is stationarily mounted inthe sup-. porting member 22 and is provided with a V-shaped recess 82having faces 83 and 84 intersecting each other at substantially a rightangle. The face 83 is adapted to form a more acute angle Wtih thevertical than the face 84. The upper edge of the face 84 terminates in aslight projection 85 employed to produce a slight bend or crimp in theleg 71 of the shape 70 when compressed by the upper die '81. The face 83of the recess 82 may be provided with various types of removable stopbrackets 86 having an abutment 87 to receive the bent portion 76 of themetal shape 70, as disclosed in FIG. 4. The stop bracket 86 may be madeof resilient material in order that that it may be clamped over the die80 as disclosed in FIGS. 4 and 8.

The upper flattening die 81 is adapted to reciprocate vertically into anout of engagement with the lower die 80. The upper die 81 comprises aV-shaped projection having faces 90 and 91 intersecting at substantiallya right angle and having the same slopes respectively as the faces 83and 84 in order that the die 81 will mate with the die 80. Formed in theface 90 adjacent the tip 92 of the upper die 81 is a rectangular shapednotch 93, interseecting the face 90 by rounded portion 94. The purposeof the notch 93 is best illustrated in FIG. 8 where the leg 75 issufliciently short that it will not be engaged by the tip 92 upondescent of the upper die 81.

The product resulting from the operation disclosed in FIG. 4 upon thebent metal shape is disclosed in FIG. 5 as a 1-inch standing S-bar sliplock 100 locking the adjacent ends of two ducts 10 1 and 102. The openend of the duct 101 slips between the legs 71 and 73, white the open endof the duct 102 slips between the legs 72 and 73 and are held togetherby the tension in the legs created by the flattening dies 80 and 81. Theupstanding reinforcing rib 105 is formed by the legs 74 and squeezedflat against each other between the respective mating faces 83 and 90 ofthe flattening dies and 81. A slight bend or crimp 106 appears in theleg 71 in exaggerated form in FIG. 5 to create a better seal between theslip lock 100 and the duct 101.. As previously mentioned, such a crimp106 is produced by virtue of the projection in the face 84 of the lowerflattening die 80.

As previously mentioned, FIG 6 discloses the modification in which theinsert block 63 has been removed from the die 23 and the insert block 62has been inserted into the recess 60 of the upper bending die 24 inorder to produce a 1 /2 inch standing S-bar slip lock. The bent shape 70formed by the modified arrangement of the dies 23 and 24 disclosed inFIG. 6, is disclosed in FIG. 7 as having substantially the sameconfiguration as the bent shape 70 disclosed in FIG. 3, except that theleg 74 is /2 inch longer than the leg 74. The lengths of the legs 75 and75 may be determined by lateral adjustment of the abutment bar 26.

The operation of the flattening dies 80 and 81 upon the bent shape 70 isdisclosed in FIG. 8, where the tip 92 of the die 81 descends past thefree end of the leg 75 which is caught by the upper side of the notch 94to start the bending operation. Otherwise, if the notch 93 were notprovided, the face would engage the free end of the leg 75 and the forceof the descending die 81 would be substantially transmittedlongitudinally, instead of transversely, of the leg 75 The product ofthe operation of the flatening dies 80 and 81 in FIG. 8 is disclosed asa 1 /2 inch standing S-bar slip lock 190 in FIG. 9. Besides thereinforcing rib 165 being /2 inch longer than the rib 105, the functionof the slip look disclosed in FIG. 9, is substantially the same as thatdisclosed in FIG. 5.

Where additional reinforcing is required in the rib a reinforcing bar110, as disclosed in dashed lines in FIG. 8, may be laid flat on the leg74 in the bent shape 70 before before it is flattened by the dies 80 and81. The resulting product 106, a 1 /2 inch reinforced standing S-barslip lock is disclosed in FIG. 10.

If desired, the bending dies 23 and 24 and the flattening dies 80 and 81may be employed to form a simple flat S-slip -lock without anyreinforcing rib, as best disclosed in FIGS. 1l14. In this modificationthe abutment bar 26 may be switched to the other side of the bendingdies 23 and 24, or the dies may be reversed, to obtain the ar rangementdisclosed in FIG. 11. 'Neither of the insert blocks 62 or 63 arerequired since no reinforcing rib is to be formed. When the upperbending die 24 descends upon the sheet metal 25, the resulting productis a substantially open S-type bent shape disclosed in FIG. 12 havingparallel legs 171 and 172 connected at opposite ends by the diagonal leg173. The bent shape 170 is then inserted in the lower flattening die 80,as disclosed in FIG. 13, for flattening by the upper die 81. In thisoperation, the notch 93 has no function and the stop bracket 86 isremoved. The resulting product, a flat S-slip lock 200, is disclosed inFIG. 14 locking the adjacent ends of the ducts 101 and 102.

The above invention therefore provides a method and apparatus forrapidly bending sheet metal in only two steps to form S-type slip locks.ioreover, the invention contemplates the employment of only two sets ofdies, each set having a novel configuration, and both sets of dies areadapted to be employed in the same conventional press brake, if desired.The dies are so designed that they can operate quickly and smoothly toform uniform bends in sheet metal with a minimum of travel of the metalrelative to the die faces. Moreover, the construction of the dies issuch that the travel is equally divided on both sides of the tip 35 ofthe projection 30 on the bending die 23.

-Deep forming of the bends in the sheet metal is also facilitated byproviding the shallow recesses 31 and 32 on opposite sides of theprojection 30 so that the maximum height of the walls 36 and 38 is /2inch as compared to a height of at least 1 7 inches for the projection30. Rounding off the edges 40 and 42 and sloping the face portions 41and 43 also provide smoother operation of the dies 23 and 24 in formingthe deep bends in the shapes 7%), 70 and 170.

The invention is also adapted for versatility in forming S-type sliplocks of various specified designs and dimensions by providing suchaccessories as the insert blocks 62 and 63 and by providing for anadjustable abutment bar 26.

It will be apparent to those skilled in the art that various changes maybe made in the invention, without departing from the spirit and scopethereof, and therefore the invention is not limited by that which isshown in the drawings and described in the specification, but only asindicated in the appended claims.

What is claimed is:

1. An apparatus for forming an S-type slip lock comprising a pair ofmating dies, means for relatively moving said dies towards engagementand away from each other, one of said dies comprising a V-shapedprojection having a first face parallel to the direction of relativemovement, said projection having a second face sloping away from saidfirst face and terminating in a shallow recess, said recess having aface opposing said second face and parallel to said first face, saidother die having a complementary face adapted to engage said one die toform an S-shaped bend in sheet metal, and means for flattening saidS-shaped bend.

2. The invention according to claim 1 in which said recess is V-shapedand said V-shaped projection extends substantially beyond the oppositeface of said recess towards said other die.

3. An apparatus for forming an S-type slip lock comprising a pair ofmating dies, means for relatively mow'ng said dies towards engagementand away from each other, one of said dies comprising a V-shapedprojection having a first face parallel to the direction of relativemovement, said projection having a second face sloping away from saidfirst face and terminating in a shallow V-shaped recess, the outerextremity of said projection forminga rounded surface connecting saidfirst and second faces, said second face forming one wall of saidshallow recess, said recess having an opposite wall parallel to thefirst face of said projection, said projection extending substantiallybeyond the opposite Wall of said recess towards the other die, asubstantially channel-shaped recess formed in said one die adjacent saidprojection, said first face forming one wall of said channel-shapedrecess, the opposite wall of said channel-shaped recess being parallelto and substantially shallower than said first face, the bottom of saidchannel-shaped recess forming an obtuse angle with the first face ofsaid projection, said other die having complementary faces adapted toengage said one die to form open bends in sheet metal in accordance withthe configuration of said dies, and means for flattening said bends.

4. The invention according to claim 3 in which the outer edges of saidopposite walls of said V-shaped and 6 channel-shaped recesses formrounded portions which terminate in plane surfaces sloping away fromsaid projection and said other die.

5. The invention according to claim 3 in which said means for flatteningsaid bends comprises a second set of dies, one of said dies comprising aV-shaped recess and the other of said second set of dies comprising amating V-shaped projection having a notch formed in one face thereofspaced proximate to the tip of said projection.

6. The invention according to claim 3 in which means are provided forvarying the width of said channel-shaped recess and the mating face ofsaid other die. 7. The invention according to claim 4 in which theopposite walls of said recesses are substantially equal in height andsaid terminating plane surfaces slope at substantially 45 angles to thedirection of relative movement of the dies.

8. The invention according to claim 7 in which the height of the firstface of said projection is at least twice the height of either oppositewall of said recesses.

9. The invention according to claim 1 in which abutment means areprovided adjacent the dies to engage the edge of sheet metal insertedbetween the dies.

10. An apparatus for forming an S-slip lock comprising first and secondsets of dies, each set comprising a pair of dies adapted to be movedrelatively toward engagement with and away from each other, one of saiddies in said first set comprising adjacent first and second projections,said first projection extending substantially beyond said secondprojection, each projection having a plane corresponding sidesusbtantially parallel to the direction of relative movement of the diesin said first set, the other side of said first projection forming aplane surface sloping between and connecting said corresponding sides toform a recess between said projections, said one die having anothersurface adjacent the parallel side of said first projection forming anobtuse angle with said parallel side, said other die in said first sethaving complementary surfaces adapted to engage said one die in saidfirst set, said second set of dies comprising a first die having aV-shaped recess and a second die having a V-shaped projection adapted tomate with said recess, said V-shaped projection having a notch formed inone face thereof spaced proximate to the tip of said projection.

11. An apparatus for forming an S-slip lock comprising a set of bendingdies and a set of flattening dies, each set comprising first and secondcomplementary mating dies, means for relatively moving said dies in eachset towards engagement and away from each other, said first bending diecomprising a V-shaped projection having a first face parallel to thedirection of relative movement, said projection having a second facesloping away from said first face and said second bending die, aV-shaped recess formed in said first bending die, said second faceforming one wall of said V-shaped recess, said recess having an oppositewall parallel to said first face, a channelshaped recess formed in saidfirst bending die, said first face forming one wall of saidchannel-shaped recess, said channel-shaped recess having an oppositewall parallel to said first face, the bottom of said channel-shapedrecess being substantially fiat and forming an obtuse angle with thefirst face of said projection, said projection extending substantiallybeyond the opposite walls of said recesses towards said second bendingdie and having a rounded surface connecting said first and second faces,the opposite walls of said recesses being of substantially equal heightand terminating in rounded portions which slope away from saidprojection and said second bending die at substantially 45 angles to thedirection of relative movement of the bending dies, said second bendingdie comprising a V-shaped recess of the same configuration as theprojection on said first die and having projections of substantially thesame configuration as the recesses in said first die to form open bendsin sheet metal having the configuration of the said bending dies, saidfirst flattening die comprising a V-shaped recess, the Walls of whichare substantially normal to each other, said second flattening diecomprising a V-shaped projection of the same configuration as the recessin the said first flattening die, said second flattening die having anotch formed in one face thereof spaced proximate to the tip of saidprojection for engaging the upper edge of a piece of sheet metal bent bysaid bending dies and located directly in the path of said notch.

12. The invention according to claim 11 in which the wall of saidV-shaped recess in said first flattening die which mates with saidun-notohed surface of the projection in said second flattening die has aprojection 'at its 'outer extremity for crimping a portion of said sheetmetal.

13. The invention according to claim 11 in which detachable stop meansare provided to fit over said first flatening die to receive a bentportion of sheet metal to be flattened between the notched face of theprojection of said second flattening die and the mating face of saidfirst flattening die.

References Cited in the file of this patent UNITED STATES PATENTS2,847,052 Hardrnan Aug. 12, 1958 2,847,053 Hardman Aug. 12, 1958 FOREIGNPATENTS 328,890 Great Britain May 8, 1930 642,340 Great Britain Aug. 30,1950

